The present invention relates generally to agricultural machinery and more particularly to measuring the drawbar pull on a tractor.
Plow depth control, also referred to as draft control, on a three-point hitch tractor mount has been manually controlled in the past by the tractor operator. As the ground becomes more resistant to the plow, the tractor engine lugs down along with the tractor speed until either the engine stalls or the operator lifts the plow to a shallower depth so that the pulling resistance is decreased.
This can also be accomplished automatically wherein the drawbar pull is sensed and the plow is raised whenever the load begins to exceed the capacity of the tractor. When soft ground is again engaged, the plow is automatically lowered to a preset depth. This can be controlled in a practical manner by placing a measuring device built into the lower link of a tractor three-point hitch which determines the tension force in that lower link. A conventional three-point hitch consists of one upper link and two lower links connecting an agricultural or construction tractor to a plow implement being pulled, and ordinarily includes a lift linkage to set and hold the plow depth of the trailing plow implement.